TLC has racked up an impressive list of celebrities willing to dig into their family's history for all to see when it begins airing the eight-episode fourth season of "Who Do You Think You Are?" on Tuesday, July 23 at 9/8c.

Produced by Lisa Kudrow and Dan Bucatinsky's Is Or Isn't Entertainment and Shed Media, the series was canceled by NBC after its third season. Martin Sheen, Rob Lowe, Blair Underwood, Sarah Jessica Parker and Paula Deen are among those who appeared on the show's NBC run.

Ancestry.com will also continue as a sponsor and primary research tool on the series.